Method for producing continuous, pneumatic tubular packings, for storate tanks, and related pneumatic packings



Feb. 7, 1967 F. MICHIELIN 3,302,952

METHOD FOR PRODUCING CONTINUOUS, PNEUMATIC TUBULAR PACKINGS, FOR STORAGE TANKS, AND RELATED PNEUMATIC PACKINGS Filed April 29, 1964 2 Sheets-Sheet 1 Feb, 7, 1967 Filed April 29, 1964 F. MICHIELIN METHOD FOR PRODUCING CONTINUOUS PNEUMATIC TUBULAR PACKINGS FOR STORAGE TANKS AND RELATED PNEUMATIC PACKINGS 2 Sheets-Sheet 2 WW1? wggu w I 1 United States Patent METHOD FOR PRODL CING CONTINUOUS, PNEU- MATIC TUBULAR ,PACKINGS, FOR STORAGE v r g rrs, AND RELATED PNEUMATIC PACK- Franco Michielin, Milan, Italy, assignor to ISOPREN S.r.L., Milan, Italy, an Italian limited-liability company Filed Apr.'29,-1964, Se'r. No. 363,486

i 8' Claims. (Cl. 277--34.3)

This invention relates to a method for producing very long, continuous tubularpackings, particularly designed to be fitted to the outer-surface of floating covers'of storage tanks for crude oil, and oil products .in general (which are usually called stockage tanks in that branch of industry), in order to maintain a substantially tight seal between the floating cover and the tank inside wall.

The invention is directed also to the long, continuous tubular packings made by such method, and in particular to a plurality of intercommunicating tubular members, that form together a ring, which can be inflated and kept under a slight overpressure, thereby cooperating with the outer contour of the floating cover of tanks of the abovestated type.

As well known, great difliculties are encountered in ensuring an essentially tight seal between the floating covers of large storage tanks (which may have diameters well over 100 ft.) and the related cylindric inner wall thereof. For obvious reasons, a rather great radial spacing must be maintained between the outer contour of the rigid cover, and the inside, cylindric wall of tank. In fact, the floating cover is not only moved continuously up and down within the tank, to follow the level variations of contents thereof, but is also subject to not negligible lateral thrusts, in particular under the action of wind. In general, such floating covers are fitted with an annular sealing crown, made by the so called sliding plate springs, and designed to be kept continuously into contact with the inside cylindric surface of the tank.

An object of this invention consists in the provision of a continuous tubular packing, made in particular of hydrocarbon proofed rubber, and designed to be interposed as a crown between the contour of a floating cover rigid structure, and said sliding plate spring, to elastically expand the latter plate spring by the action of a pneumatic pressure obtained by inflating said tubular packing with air or inert gases, the single sections of said packing being in communication with each other, to ensure a consistent distribution and equalization of pressure in all points thereof.

Particular difficulties are encountered in carrying the above object into practice. Such difliculties mainly consist in the sizes and weight of tubular packing, in the great length thereof (up to 150 and more linear meters), whereby the packing must be made of a plurality of single sections, to be joined with one another. Such sections, according to present technical knowledge, ought to be coldwelded together. However, such joining method is impractical due both to 'difliculties encountered in the mechanical application thereof, and to poor efficiency of the joints that are obtained.

But even assuming the possibility of obtaining such packing in one piece only, then practical problems would 3,362,952 Patented Feb. 7, 1967 arise, owing to difficulty of transport and installation. Moreover, in the case of local breakage of a tubular packing of the kind specified above, made either in one piece or as a plurality of single sections welded with one another, great expense would be involved in its replacement.

The method according to the invention essentially consists in having the continuous tubular packing constituted by a plurality of single tubular sections that can be buttconnected with oneanother, by means enabling mutual communication-between the interiors of adjacent elements, such sections being associated with sleeve couplings, fitted in the joints, and forming lengths of a toroidal (orpractically cylindric, owing to very large bending radius of the packing, inrespect of the diameter thereof) surface'for the installed packing.

In particular, by making the packing as a composite structure, as stated above, each single component thereof can be molded in one piece only, i.e. without weak points, or of parts added after the vulcanization, which are made of hydrocarbon proofed rubber, by the molding and curing procedures already well known in'the art.

The mechanical and pneumatical connection of said elements may advantageously be made by means of metal muff couplings, and the gap left between the thus connected sections is filled by said sleeves, having an OD. equal to that of said section, which haveends with a slightly reduced diameter, whereon'said sleeves are forced.

Many practical, operational and technical advantages are thereby obtained. Thus, for instance, the pneumatic packing does not show any broken connections between the single sections nor are the joints formed by procedures such that a safe sealing is not thoroughly ensurede.g. a connection of already vulcanized components, made by self-vulcanizing rubber solutions which, as already well known, under the .action of vapor of hydrocarbons stored in the tank, would whollyllose their'already poor efficiency. Conversely such connection is made by the use of metal components according to the invention.

Moreover, by merely disconnecting and refitting said components, that may consist, e.g. of screw couplings, the possibility is given to have anyone of said main components replaced by a new one.

For suitably inflating the tubular packing, a component inclusive of a branch connection, e.g. a T-fitting, can be utilized for coupling two or even more packing sections with each other. Such T-fitting may be inserted also between the metal coupling elements.

Even 'by making very long single sections, e.g. 20 or 25 meterslongsections, in order to minimize the number of joints, the industrial production of same sections would be always practicable, and the transport, handling and installation thereof, for forming in situ the required continuous packing, would not give rise to practical difiiculties.

The above and further features and objects of the inventive .concept will bebetter appreciated from a consideration of the following detailed description of an embodiment of the invention, with reference to the accompanying drawing, wherein:

FIG. 1 is a diametr'al longitudinal section, partly broken away, ofa length of a tubular packing according to the invention, inclusive of a coupling point between two adjacent sections.

FIG. 2 is an exploded, partly sectional side view of components of the section shown in the FIG. 1, inclusive of a complete packing section, that is shortened in the drawing, for reasons of space.

FIG. 3 shows an additional series of coupling components, for the fitting of a T-connection whereon the pneumatic pressure may be applied as required for inflating the packing.

FIG. 4 shows a modification of the embodiment of the coupling shown in the FIG. 1, where supplemental components as shown in FIG. 3 and of a suitably shaped sleeve for guiding and securing the packing are added.

FIG. 5 is a cross-section of said sleeve, taken on the line 5-5 of FIG. 4.

FIGS. 6 and 7 are side views, partially broken away, showing the essential steps of the procedure to be employed for the connection of two packing lengths, and

FIG. 8 is a simplified section of the installed packing, taken in a radial plane in a storage tank with a floating cover.

Referring now to the'drawings, as shown in FIGS. 1 and 2, the packing is comprised of a plurality of main tubular; elements, as indicated at 10, and the principal component of which consists of a cylindrcial pipe 11, having e.g. an CD. of the order of 200 mm., and a wall thickness of the order of 6 mm.; of course, such values are by way of example only, as they may vary within wide limits, according to different specific requirements and to convenience of production and of operation.

Said main components, made of rubber, and in particular of a hydrocarbon resistant synthetic rubber, are formed with heads 12, having an outer diameter smaller than that of the middle portion of the component, as well as with end sections 13, that maybe e.g. 130 mm. long, and the outside diameter of which is smaller than that of the main body portion 11 by an amount equal to the double wall thickness of sleeves 14, which in turn have an OD. equal to that of main body 11. The wall thickness of said sleeves may be e.g. of the order of 8 mm.

The sections 11 and 13 of each main component are connected with one another by tapered portions 15, preferably inclined at 45 deg, and accordingly the edges of said sleeves 14 are also countersunk at 45, with oblique sides, as indicated at 16 in FIG. 2.

By the use of threaded sleeves 17, that are fastened to heads 12 of each main component, e.g. by clamping between an inside projecting flange 18, and a washer 19, that cooperates with a lock nut 20, the adjacent main components can be connected pneumatically and mechanically with each other, e.g. through a pipe union 21, preferably formed with a cone seat, thereby establishing a connection, e.g. as shown by way of example in FIG. 1.

The length of sleeve 14 must be such that, after having established the connection, it is forced over both reduced diameter end sections 13 of adjacent, butt-connected main components, in order to form a substantially continuous outer surface throughout the length of the composite packing thus obtained.

The procedure to be followed for joining the single packing sections with one another, is shown in FIGS. 6 and 7. First of all, and obviously with sections not yet pressurized, a sleeve 14 is slipped over the end of a'main element 10, forcing it beyond the portion 13, advantage being taken, for such a purpose, of the deformability of material, e.g. as shown in FIG. 7, After having joined the metal'components together, the sleeve 14 is slipped back in the coupling zone, that is the position, as shown in FIG. 1.

For inflating the thus obtained tubular packing with air or an inert gas, a metal T-fitting 30 (see FIGS. 3 and 4) can be inserted in one or more joints, by having it connected with the pipe union 21, e.g. by means of a double nipple 31, fitted with a central nut 31. In such a case, a longer sleeve 114 is substituted for the tubular sleeve 14, as shown in FIGS. 1, 2, 6, and 7, to allow for the greater spacing between the main element, as required for the fitting of the auxiliary components that are separately shown in FIG. 3, sleeve 14 preferably being formed with a transverse groove .32, designed for the guide of a storage tank floating cover.

The application of such an annular packing between the inside wall of a cylindrical tank S, and the outer surface or circular crown C of floating tank cover T, as well as the operation thereof, is shown by way of example in FIG. 8. Said tubular packing, made-up by a pluraltiy of main elements 10, associated with each other, and cooperating as stated above, is interposed between the outer side of said cover crown C, and the sliding plate L, adapted to make a sliding fit with the inside wallof tank S, said packing being supported at suitable intervals by suspension straps F.

The pneumatic pressure,'as applied inside 'of the packing, is obviously wholly uniform throughout its length, owing to the continuity of the inside communication, and acts in a manner much more completely and efliciently compared to previous use of counterweights, elastic plates, rubberized canvas," plastics laminated fabrics and the like. Thereby there is ensured a seal between cover and tank; moveover, the packing allows for wide variations by deformation, and the wind pressure is conveniently resisted.

Both the method, and the resulting means that form the objects of the invention, have been shown and described merely as not restrictive examples, and it must be understood that many changes and modifications and adaptations to specific installation and operational requirements may be made thereto, within the scope of the appended claims.

What I claim is:

1. Apparatus for forming an annular seal between a round vessel and a slidable cover therefor, said apparatus comprising a plurality of flexible hollow bodies of substantially cylindrical shape adapted for being inflated, means connecting adjacent bodies together at their ends to form a continuous annular arrangement while providing communication between the interiors of said bodies,

said bodies having end portions of reduced diameter, and sleeve means surrounding the end portions of adjacent bodies and mounted thereon to enclose the first said means, said sleeve means having an' outer surface which is flush with the outer surfaces of the bodies and which forms a substantially continuous surface therewith.

2. Apparatus as claimed in claim 1, wherein said means connecting adjacent bodies together comprises a fitting secured to each body at an end thereof and a connector detachably connected to the fittings of adjacent bodies.

3. Apparatus as claimed in claim 1, wherein each said body includes a stepped portion joining each end portion to the remainder of the body, said sleeve means comprising a sleeve member for surrounding the end portions of adjacent bodies, each sleeve member having opposite ends abutting the stepped portions of adjacent bodies.

4. Apparatus as claimed in claim 2, wherein each body is a one-piece member and is hydrocarbon-resistant, said member having a wall at each of its ends for receiving one of the fittings.

5. Apparatus as claimed in claim 2, wherein said'fittings and connectors maintain the ends of the bodies in spaced relation.

6. Apparatus as claimed in claim 5, wherein at least one of the connectors has an opening for the supply of pressure fluid for inflating the cylindrical bodies.

7. A method of forming an inflatable seal between a round vessel and a slidable cover therefor, said method comprising connecting a plurality of inflatable flexible tubular bodies together at their ends to form an annular 6 arrangement of said bodies between the vessel and the References Cited by the Examiner cover, and wherein the bodies are in communication with UNITED STATES PATENTS one another at their lntenors, PI'OVldlIlg a flexible tubular sleeve at one end of each body, each sleeve being re- 741,526 10/1903 fi l 9 314 tracted onto its associated body prior to the connection 5 2,326,987 8/1943 Wemhmmer 9 314 of the end of the body with the end of an adjacent body, 2332514 4/1958 Settle 277 226 XR sliding the sleeves over the adjacent ends of the attached 3228702 1/1966 Ulm et 27734'3 bodies after the bodies have been connected. FOREIGN PATENTS 8. A method as claimed in claim 7, wherein the bodies 1 3 3 9 19 4 France are connected together in detachable fashion with their It) ends in spaced relation. SAMUEL ROTHBERG, Primary Eramz'ner. 

1. APPARATUS FOR FORMING AN ANNULAR SEAL BETWEEN A ROUND VESSEL AND A SLIDABLE COVER THEREFOR, SAID APPARATUS COMPRISING A PLURALITY OF FLEXIBLE HOLLOW BODIES OF SUBSTANTIALLY CYLINDRICAL SHAPE ADAPTED FOR BEING INFLATED, MEANS CONNECTING ADJACENT BODIES TOGETHER AT THEIR ENDS TO FORM A CONTINUOUS ANNULAR ARRANGEMENT WHILE PROVIDING COMMUNICATION BETWEEN THE INTERIORS OF SAID BODIES, SAID BODIES HAVING END PORTIONS OF REDUCED DIAMETER, AND SLEEVE MEANS SURROUNDING THE END PORTIONS OF ADJACENT BODIES AND MOUNTED THEREON TO ENCLOSE THE FIRST SAID MEANS, SAID SLEEVE MEANS HAVING AN OUTER SURFACE WHICH IS FLUSH WITH THE OUTER SURFACES OF THE BODIES AND WHICH FORMS A SUBSTANTIALLY CONTINUOUS SURFACE THEREWITH. 